- Environmental Services
- What We Do
- Wastewater Services
- Overflow Control Plan
- Inflow & Infiltration
- Public Sewer Rehabilitation Program
Public Sewer Rehabilitation Program
Since 1995, the City of Springfield has engaged in an active rehabilitation effort to reduce the entry of inflow and infiltration and extend the usable life of the community’s aging sanitary sewer system. More than $86 million is currently budgeted out of the Supplemental Overflow Control Plan to support Public Sewer Rehabilitation strategies.
Public Sewer Rehabilitation efforts include:
Cured-in-Place Pipe Lining (CIPP)
Cured-in-place pipe lining involves a felt bag, matching the diameter of the damaged pipe, being inserted into the pipe between manhole locations. The bag is then inflated and filled with steam to cure the resin within the felt, forming a stand-alone pipe within the original pipe. The stand-alone pipe helps prevent water from entering, prevents roots from extending into the main and causing blockages, and adds structural integrity. This renewal strategy is appropriate when there are smaller cracks and anomalies in the pipe that still allow the equipment to travel through the main and not damage the felt bag during installation.
The City has over 29,000 manholes in its system of varying construction, depth, and age. These manholes are placed at changes in pipe alignment and where periodic access is required for proper maintenance of the pipe. Similar to the system piping, manholes can develop cracking in walls, leaks around areas where piping enters or exits, or can suffer from complete structural failure of wall sections, any of which can allow inflow and infiltration to occur. Manholes are one of the more expensive collection system components to repair and/or replace.
To date, the City has recorded when its maintenance crews encounter a manhole with defects that are visually apparent. A follow-up assessment is made of the extent and type of repairs that are needed. Various rehabilitation methods and products are used to then make needed repairs.
This is another in-place renewal strategy that is focused on jointed pipes, typically of larger diameter (24” or larger). These pipes are typically made of concrete and are jointed together with or without a gasket. A specialized machine is placed into the sewer pipe and traverses the length of the pipe, stopping to test each joint. The joint is tested to determine its ability to withstand pressure and, if the joint shows failure, a two component flowable chemical grout, somewhat like a silicone calking a homeowner might use to seal joints, is injected into the joint and quickly sets up to form a flexible seal of the joint. This can be done while the line is in-service.
While pipe lining and grouting are utilized to seal leaks that have formed at cracks and joints, other defects are so large they require the broken pipe to be physically replaced. This involves excavating down to the pipe, which is typically between 6 to 15 ft in depth and removing the broken sections and replacing with new pipe. Since the line cannot remain in service during this repair, pumping operations are used to bypass the area under repair. Due to the costs of excavation and by-pass pumping, open-cut repairs are typically the most expensive form of pipe renewal strategies. Open-cut repairs are completed by both in-house crews and contractors to support cured-in-place lining.